Physics Nobel honours Francis Halzen and IceCube’s view of the cosmos

Announced October 6, the award recognises a new means of observing the universe, developed over decades with an international collaboration. [1][5]

The instrument turns roughly a cubic kilometre of Antarctic ice into a detector. A neutrino occasionally interacts with matter and produces charged particles. Their light reaches buried sensors; its pattern and timing allow researchers to reconstruct the event. The photograph shows one such optical module being lowered into an ice borehole. [2][4][5]

This is useful because neutrinos carry no electric charge: magnetic fields do not deflect them as they do charged cosmic rays. Their arrival directions can therefore help investigate distant high-energy sources. Most neutrinos pass through the detector without interacting, which explains the need for such an enormous observing volume. [2][5]